description of distcc protocol version 2
Copyright (C) 2003 by Martin Pool

disclaimer
----------

This document is provided as explanation for people developing or
debugging distcc.  Discrepancies between this document and the distcc
code are an error in the document.

This document is intended to describe distcc 2.9.

Because this program and document is licensed free of charge, there is
no warranty of any kind, to the extent permitted by applicable law.

If anything is unclear, please ask on the mailing list.


protocol
--------

Protocol 2 is a variation of protocol 1.  It gets a new version number
because that's the simplest way to indicate the change.

The protocol number (DIST) sent by the client is set to 2.  The server
must respond (DONE) in version 2.

The content of the "bulk" tokens (DOTI, DOTO, SERR, SOUT) are
compressed using the LZO1X algorithm.

The token parameter gives the length of the compressed form.

As a special case, if the uncompressed form is zero bytes, then it is
not compressed but rather sent directly as zero bytes.  (Compression
slightly expands a zero byte string.)

The distcc client and server can handle either protocol 1 or 2
depending on whether the user configures compression on.